1. Field of the Invention
This invention relates to an apparatus and process useful for subcutaneously implanting biologically acceptable pellets in animals. More specifically, it relates to an apparatus which allows a needle containing the pellets to be subcutaneously inserted in the animal, then retracted from around the pellets, thus implanting the pellets.
2. Prior Art
It is generally known in the art that it is desirable in some cases to subcutaneously implant medicament containing pellets in some domestic animals such as cattle, sheep, horses, pigs, etc., to obtain a desired result such as weight gain, contraception, estrus suppression, or disease treatment. In the past pellets were implanted using devices wherein the pellets were pushed out of a needle using a plunger of some sort. With these devices, one would either (a) insert the needle to the desired depth to establish a subcutaneous channel then force the pellets out of the needle while manually withdrawing the needle and device to deposit the pellets along the channel or (b) insert the tip of the needle subcutaneously then force the pellets under the skin, the pellets forming a channel themselves as they are forced out. In either case much pressure is placed on the pellets and they would disintegrate, crack or otherwise become damaged upon deposition to alter the delivery characteristics, unless great care was taken. In the case where a plurality of pellets were to be implanted from one needle, sometimes all the pellets could not be deposited at one place. Patents which represent these devices include U.S. Pat. No. 2,907,327 to White; Australian Pat. No. 253,175 to Boots Pure Drug Co.; U.S. Pat. Nos. 1,347,622 to Deininger; 2,761,446; 2,883,984 to Candido et al.; 3,058,465 to Bell; 3,402,712 to Eisenhand; 3,520,299 to Lott et al.; 3,538,916 to Wiles; 3,669,104 to Wyatt et al.; 3,774,607 to Schmitz; and 3,921,632 to Bardani.
The difficulties inherent in the prior art can be substantially eliminated by the apparatus and process of the present invention. In the apparatus of this invention, the pellet-containing needle is attached to a carriage which is retracted after the needle is subcutaneously inserted in the animal, thus leaving the pellet or pellets implanted in the animal in the channel preformed by the insertion of the needle.